Adrian Merritt 1 NSF REU program at UIC, 7/29/2010

UIC Physics I. Research Objectives and Methods II. Sample Characterization III. Particle Size Results IV. Research Conclusion V. Future Work NSF REU program at UIC, 7/29/2010 2

UIC Physics  The core objective is to better understand how the manganese promoter affects the rhodium catalyst performance  Some current possibilities are: Particle size Oxide species Changes to interfacial interaction Formation of surface oxides NSF REU program at UIC, 7/29/2010 3

UIC Physics  Due to the de Broglie wavelength, electron microscopes can have a fundamentally finer resolution than light microscopes  Electrons passing through the sample are scattered by various mechanisms  Spatial, mass/thickness and analytical information is available from the scattered electrons NSF REU program at UIC, 7/29/ Image from Transmission Electron Microscopy, B. Williams and C. Carter, volume IV

UIC Physics  Invented by Franz Fischer and Hans Tropsch  Utilizes syngas to produce hydrocarbon products (methane, ethanol, diesel and gasoline fuels)  Syngas is a mixture of CO and H 2, which can be produced from coal gasification, natural gas, or biogas, and is used as the base feedstock for the process  In all cases though, the reaction relies upon the proper catalysts for selectivity and efficiency NSF REU program at UIC, 7/29/2010 5

UIC Physics  Rhodium is a useful catalyst for the FT process as it lies at an intermediate mass level and so works to create ethanol for use as an alternative fuel source  Manganese acts as a promoter, which changes the effects of a catalyst without being a catalyst itself  Manganese improves the selectivity and overall efficiency of rhodium catalysts for the FT process  E.g. from T. Feltes: 1% Mn loading on 3% Rh on SiO 2 support raises CO conversion ten fold and increases ethanol selectivity from 0.0% to 9.2% NSF REU program at UIC, 7/29/ Image from The Selective Adsorption of a Manganese Promoter Over Supported CO Hydrogenation Catalysts, Theresa E. Feltes, 2010

UIC Physics  Carbon film on copper support grid  d = 3 mm  Allows deposition of catalyst particles and easy viewing  Powdered samples are prepared by dry impregnation (DI) or strong electrostatic adsorption (SEA) NSF REU program at UIC, 7/29/2010 7

UIC Physics  Final sample has many medium-sized clusters of silica particles  Best (most useful) clusters are those overhanging an edge (reduces impact of C-film) NSF REU program at UIC, 7/29/2010 8

UIC Physics  Rhodium on silica, 3% loading by DI  Rhodium on silica, 3% loading by DI with 1% manganese  Calcination at 350° C for 4 hours in air  Reduction (when applicable) at 300° C for 2 hours under H 2 flow NSF REU program at UIC, 7/29/ Images from The Study of Heterogeneous Catalysts by High-Resolution Transmission Electron Microscopy, A. Datye & D. Smith, Catalyst Review, 1992

UIC Physics  Typical magnification is x300k  Use diffraction contrast imaging to differentiate rhodium particles (crystalline) from the silica support (amorphous) NSF REU program at UIC, 7/29/

UIC Physics NSF REU program at UIC, 7/29/ Averages: 3.12 nm vs nm Standard deviations: 0.80 nm vs nm The same (within experimental limits)!

UIC Physics NSF REU program at UIC, 7/29/ Averages: 2.26 nm vs nm Standard deviations: 0.54 nm vs nm

UIC Physics NSF REU program at UIC, 7/29/ Averages: 2.55 nm vs nm Standard deviations: 0.91 nm vs nm Heated at 300° C for 2 hours, then allowed to cool

UIC Physics SampleAverage Particle Size (nm) Standard Deviation (nm) RhO x (unreduced) Rh Rh+Mn O x (unreduced) Rh+Mn Rh+Mn (in situ heating) Rh+Mn (after cooling)  Averages not different enough to cause all phenomena observed in catalysts with a promoter NSF REU program at UIC, 7/29/

UIC Physics  Catalyst particle size has been ruled out  Next step is JEOL JEM-2010F work Better resolution through Z-contrast imaging EELS setup  EELS allows changes in electronic structure to be characterized  Together, allows better characterization of structure NSF REU program at UIC, 7/29/

UIC Physics  University of Washington ab initio program for simulation EELS spectra  Full multiple scattering simulation  Preparation for JEM-2010F EELS work, distinguishing rhodium oxide species NSF REU program at UIC, 7/29/

UIC Physics  National Science Foundation and Department of Defense for funding, EEC- NSF Grant #  Professors Takoudis and Jursich as REU organizers  Professor Robert Klie as PI  Yuan Zhao as mentor  Ke-Bin Low for TEM training and aid  The RRC for its support in TEM work NSF REU program at UIC, 7/29/